Absent Mr Blue Tit

Hi on our of our BT boxes with a camera in our garden, we have Mrs BT having only recently laid 7 eggs (thought this was quite late!) however whilst Mr BT actively took part in nest box selection, he left the nest building to Mrs BT. I believe Mrs BT has now laid all her eggs as nothing laid in last 2 days and looks like she is now incubating them. But I was expecting Mr BT to pop in occasionally to keep her topped up with food etc, but no sign of him. If he doesn’t reappear, is it likely that Mrs BT will be able to continue incubating and popping out when she can for food but more importantly, are the chicks likely to survive once hatched with a missing parent to help with food/poo duties? Any advice gratefully received especially if there is anything I can do to improve survival rates, many thanks